The family Centetidae (= Tenrecidae) includes 10 recent genera which are all endemic to the island of Madagascar (Simpson, 1945). The genus Cryptogale is probably extinct, and Dasogale has only been collected twice. The remaining eight genera fall into two distinct subfamilies, the Centetinae (= Tenrecinae) which possess spines; and the Oryzorictinae which are characterised by their small size and soft pelage. The Centetinae includes four common genera: Centetes, Hemicentetes, Echinops, and Setifer.

Both Echinops and Setifer are covered on their dorsum with stout spines and have the ability to roll into an impregnable spiny ball. In this respect they are strongly convergent with the old world hedgehogs (Erinaceidae). Centetes (= Tenrec) is quite large, reaching a length of 0.40 to 0.45 m. The spines are somewhat reduced, and in some geographical races the long, guard hairs virtually mask the spines with the exception of the nuchal crest area where the spines are usually visible. Hemicentetes is striped, black and white in the species nigriceps; yellow and black in the species semispinosus. The spines of Hemicentetes are barbed and detachable, and in its offensive behaviour patterns it will attempt to drive the nuchal spines into an enemy. The Oryzorictinae are quite small and little studied. Limnogale has webbed feet and is semi-aquatic and quite distinct as a genus. Oryzorictes is mole-like and semi-fossorial, whereas Microgale and Geogale are more like the temperate shrews in their appearance and behaviour. Further references on the behaviour and ecology of these mammals may be found in a recent publication by the authors (Gould and Eisenberg, 1966).

To date we have maintained the following species in captivity: Centetes ecaudatus, Hemicentetes semispinosus, H. nigriceps, Echinops telfairi, Setifer setosus, Microgale (Nesogale) dobsoni, and Microgale thomasi. Captive breeding has been accomplished with both species of Hemicentetes, and with Echinops telfairi. In addition, we have accumulated data on captive reared litters of Setifer setosus and Centetes ecaudatus.

Our tenrecs have been maintained in cages of various sizes. Breeding has been accomplished by holding pairs of Hemicentetes semispinosus, H. nigriceps, Echinops telfairi in cages having a floor area of 2,000 sq. cm. Pairs of Centetes have been successfully maintained in cages having a total area of 10,400 sq. cm, and two successful breedings have been accomplished in this space. All of our tenrec species will build a nest from hay or paper strips. A nest box is highly desirable, especially for nursing females; and, coupled with nest building, the nest box permits the animal to maintain a high body temperature easily throughout lactation.

Because the feeding habits of Hemicentetes cause it to scatter its food we have spread newspapers under the feeding dishes. Sawdust is suitable as a floor covering but earth or dampened peat moss is preferable. Several Hemicentetes kept in captivity for more than one year developed swelling on the toes. A soil substrate and trimming of the toenails might have prevented this condition.

All genera of the Tenrecidae can be maintained in part with the following ration: raw, chopped horsemeat mixed with condensed milk and baby cereal (Pablum) to form a thick paste. To this basic mixture, a standard vitamin supplement (ABDEC) is added. The genus Hemicentetes presents some peculiar problems since in the wild it feeds almost exclusively on earthworms and coleopteran larvae. An active adult or growing juvenile may eat 70 g of earthworms in a 24-hourly period. We have been unable to maintain a healthy Hemicentetes colony without supplementary feedings of earthworms. It is difficult to accustom this genus to an artificial diet and we generally mix chopped earthworms and small egg noodles with the basic meat mixture during the feeding conversion. In addition, we mix more water with the meat mixture until its consistency approximates to a thin gruel.

Echinops, Setifer, and Microgale are given supplementary feedings of crickets, grasshoppers, or mealworms. During the rearing phase, lactating females and the juveniles of Centetes are given supplementary diets of earthworms. Setifer also eats earthworms readily, but Microgale generally ignores a worm supplement in preference to crickets or mealworms.

The temperature is an important variable in rearing tenrecs. In general, the Centetinae exhibit a greater thermal lability than do the other species of Microgale which we have studied. The rectal temperature of Microgale thomasi ranges from 26.0 to 30.0°C within an ambient range of 21 to 24.8°C. Although Microgale thomasi becomes very fat during the austral autumn and its tail is specialised for fat storage, it does not readily enter a profound torpid state. On the other hand, Echinops, Setifer, Centetes, and Hemicentetes exhibit a profound thermal lability. During the austral spring and summer, these genera show a 24-hour periodicity in thermoregulation with rectal temperature falling over a range of 7°C during the resting phase of their activity cycle. Pregnant or lactating females and growing juveniles tend to maintain a more regular temperature. During the austral winter these genera typically hibernate, becoming torpid for several months; however, during the austral summer Echinops will unpredictably cease feeding from time to time. The timing and duration of the hibernation period is in part a function of local conditions and all of these genera exhibit distribution patterns which include a range of elevations and climatic conditions (see Gould and Eisenberg, 1966).

In the laboratories at Washington, the animals are permitted to hibernate at temperatures rainging from 18 to 22°C. During the breeding season the animals are maintained at 23 to 26°C. These figures represent an arbitrary range based on average values derived from field measurements and as such are a compromise. However, these procedures have allowed us to breed Echinops and Hemicentetes.

Breeding success is generally optimal when a single pair is introduced to a neutral breeding cage. The male may be left with the female Hemicentetes semispinosus throughout the rearing phase, but a routine separation of the male has been instituted to insure the maximum growth rate for the young. Echinops also exhibits considerable social tolerance, but again a separation of the male at parturition is advisable.

The sex of most tenrecs can be determined by pressing the cloacal area until the penis or clitoris is exposed. This procedure is difficult to impossible with Echinops as it rolls into a tight ball when disturbed. Due to limited caging facilities and to the difficulty of sex determination, as many as five Echinops were placed in the same cage (2,000 sq. cm). Under such crowded conditions, two different females gave birth to litters that they successfully reared; however, immediately after parturition the four other Echinops were removed from the female and the suckling young.

Although Setifer and Centetes show considerable tolerance when held in groups, our behavioural data suggest that breeding success would be maximised if the animals were kept as pairs only through the period of conception. Our data on Microgale are sparse but again we urge that the animals be housed separately except for the pairing period. Considerable losses have been experienced when Microgale thomasi specimens were held in groups exceeding three in number.

The young of Centetes, Setifer, Echinops, and Hemicentetes are born in an altricial state; however, their developmental rates are very rapid. Utilising the age of eye opening as a criterion, we have found that the young Centetinae mature more rapidly than do the young of the Soricidae, Talpidae, and Erinaceidae (Gould and Eisenberg, 1966). Under optimal conditions, the females of Hemicentetes nigriceps and H. semispinosus can conceive at 28 to 36 days of age. The gestation period of Hemicentetes is quite long, exceeding 44 days in both species. The gestation period of Echinops has recently been determined accurately for three pregnancies exhibiting a range from 62 to 68 days. It may well be that all of the Centetinae have a gestation period ranging between seven and nine weeks; however, definitive data are depending on an intensive effort in our own and the breeding programmes of others.

A series of excellent papers has already been published concerning the general ecology of tenrecs (Petter and Petter-Rousseaux, 1963; Malzy, 1965); temperature regulation and activity (Herter, 1962; Kayser, 1960); and general behaviour in captivity, (Herter, 1963a,b). Certainly the recent interest in this group will ensure steady progress in our understanding of its biology.